Apparatus for processing of ophthalmic lens



April 21, 1970 O, Rum E' l'AL APPARATUS FOR PROCESSING OF OPHTHALMICLENS Original Filed Feb. 4, 1965 15 Sheets-Shet 1 FIG./

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APPARATUS FOR PROCESSING OF OPHTHALMIC LENS Original Filed Feb. 4, 196515 Sheets-Sheet 2 55 FIG. 7

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ATTORNEYS April 21, 1970 M. o. RUDD ET AL APPARATUS FOR PROCESSING OFOPHTHALMIC LENS 15 Sheets-Sheet 4 Origlnal Filed Feb. 4, 1965 ATTORNEYSApril 21, 197 0 o, RUDD ET AL I 3,507,076

-APPARATUS FOR PROCESSING OF OPHTHALMIC LENS I Original Filed Feb. 4.1965 I 15 Shts-Sheet 5 ATTORNEYS April 21, 1970 o, U D ETAL 3,507,076

APPARATUS FOR PROCESSING OF OPHTHALMIC LENS- Original Filed Feb. 4, 196515 Sheets-Sheet 6 FIG. 13 78 M N A r-i121, 1970 'Em 3,507,076

APPAEIIATUS FOR PROCESSING OF OPHTHALMIC LENS Original Filed Feb. 4,1965 15 Sheets-Sheet 7 EFB INVENTORS 1 M100. #000 y 1 AZ EXfl/VDEJP MWORD/VOA; b BY my au Camfld ATTORNEYS April 21, 1970 Manual: ETAL 3,507,76

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ATTORNEYS 15 Sheets-Sheet 9' M. O. RUDD ET AL April 21, 1970 APPARATUSFOR PROCESSING OF OPHTHALMIC LENS Original Filed Fgb. 4', 1965 M. O.RUDD ET AL APPARATUS FOR PROCESSING OF OPHTHALMIC LENS April 21, 1970 v15 Sheets-Sheet 10 Original Filed Feb. 4, 1965 F/azz WEI; ATTORNEYSApril 21, 1970 M. o. RUDD ET AL APPARATUS FOR PROCESSING OF OPHTHALMICLENS Original Filed Feb. 4, 1965 15 Sheets-Sheet 11 INVENTORS M/LO 0W00- HLEXHA DEI? M. WOA0/VOFF 5.4 hi;4. %v M ATTORNEYS April 21, 1970 o.R ET AL "3,507,076

APPARATUS FOR PROCESSING OF OPHTHALMIC LENS l5 Sheets-Sheet 12 OriginalFiled Feb. 4, 1965 F/G.Z9

INVENTORS M/LO 0 EH00 FIG. 30

15 Sheets-Sheet 1s M. O. RUDD ET AL April 21, 1970 A APPARATUS FORPROCESSING OF OPHTHALMIC LENS Original Filed Feb. 4, 1965 April 21 1970M. Ok-RUDD', ET AL 3,

APPARATUS FOR'PRIOCESSVING-OF OPHTHALMIC LENS Original Filed Feb. 4,1965 15 Sheets-Sheet 14 I ATTORNEYS April 21, 1970 I go upp ETAL 35075076 APPARATUS FOR PRQCESSING OF OPHTHALMIC LENS Original Filed Feb 4,1965 I l5 Sheets-:Sheet 15 ljI/A 7 VII/1111117 ATTORNEYS United StatesPatent 3,507,076 APPARATUS FOR PROCESSING OF OPHTHALMIC LENS Milo O.Rudd, Vision Park, and Alexander M. Woronotf, both of Fort Lauderdale,Fla. (Yacht Haven, Stamford, 'Conn.

Original application Feb. 4, 1965, Ser. No. 430,315, now Patent No.3,431,688. Divided and this application Mar. 26, 1968, Ser. No. 736,869

Int. Cl. B24b 19/00 US. Cl. 51-277 22 Claims ABSTRACT OF THE DISCLOSUREA blocker is designed to apply an indexing plug to the finished side ofa semi-finished lens blank. A support is provided for receiving thelower concave side of the blank. An outer die member is positioned onthe upper convex finished side of the blank which serves to contour theformed block with an optical axis reference. An inner mold is loweredonto the convex side of the blank within the outer mold for contouringthe block with the mechanical center reference. Means are associatedwith both of these molds for aligning them azimuthally in accordancewith the prescribed cylinder axis. Moldable blocking material isdispensed from an appropriate dispenser between the dies for forming ablock in one molding operation in a secure manner on the lens blankhaving both a mechanical center reference and a optical centerreference. Simultaneously, an index is formed on the block relative tothe ultimate horizontal alignment of the finished lens. Means are alsoprovided for removing the blocked lens from the dies upon setting of theblocking material. A turntable arrangement is also provided wherebyanother lens blank may be aligned and eventually associated with the twodie members for having a blocking material subsequently introduced andsecured thereto with references permitting the concave side of the lensblank to be finished according to prescription.

This application is a division of Ser. No. 430,315, filed Feb. 4, 1965,and now Patent No. "3,431,688.

The present invention relates to a process and to apparatus formanufacturing ophthalmic lenses to order, i.e., to prescriptionaccording to the needs of the eventual wearer or user of the lenses.

The present methods and apparatus for finishing ophthalmic lensesrequire the services of skilled technicians who laboriously determinethe manner in which a semifinished lens blank is gripped and ground,lapped, edged, etc. to produce the required lens surfaces properlyoriented when mounted in spectacle frames on the wearer. Considerabletime, and expensive labor, is involved in the present method, and thereis relatively high incidence of breakage, which of course means thatwork done on that lens is lost and must be completely renewed. Ingeneral, the optical laboratory purchases semi-finished blanks which areover-size as to area and thickness. One surface, usually the frontsurface (as mounted, or with respect to the wearer) is finished, and theother side is ground by the laboratory to prescription and the edges ofthis blank are finished, at which time the finished lens is mounted inthe spectacle frame.

There are several factors which must be taken into account by thetechnician in the optical laboratory in performing the present methodwhich results in the so-called edged lens, i.e., the finished lensprepared for fitting in the frame. The aforementioned other surface ofthe blank as a rule is generated as a toric surface, but occasionally asa spherical surface. A toric surface has different curvatures at rightangles to each other, and is thus non-spherical. This toric surface isusually cupped in as viewed from ice the rear, in which case it is knownas a minus-toric. The cylinder axis of the lens is the direction ofleast power of the toric surface, and therefore is a definition of theorientation of the toric surface with respect to the finished edgedlens. Cylinder axis is measured from horizontal in a counterclockwisedirection as viewed from the front of the lens, i.e., as viewed by anobserver, as distinguished from the wearer.

The finished lens has a so-called mechanical center which is the pointwithin the lens to which the edge of the finished lens is referred. Thisis ordinarily determined by drawing a circumscribing rectangle about thelens and locating the intersection of the bisectors of the horizontaland vertical sides of such rectangle.

The optical center of the lens is that point at which it has zero prism.It can generally be described as the point at which a beam of lightwhich strikes the lens will not be bent in passing through. Thetechnician uses a layout chart which serves to locate the point Wherethe optical center should be. In the case of bi-focal lenses which willbe used hereinafter as an example, this layout chart locates theultimate optical center of the finished lens on the blank with referenceto the bi-focal segment.

The prescription furnished to the technician specifies the type of frameand from this he can determine the lens height and width, and thedistance between lenses, which is the distance horizontally between theadjacent side edges of the lenses, across the bridge. The prescriptionalso will give the pupillary distance for the wearer. The prescriptionwill also tell, in the case of multifocal lenses, where the top of thereading segment of the lens is located with respect to the bottom of thefinished lens.

Working from the prescription, the technician, at present, positions thesemi-finished blank on a layout chart, determines the desired ultimatelocation of the optical center, and then marks on the blank the positionof this center and cylinder axis line as determined by prescription. Headheres a block to the finished side of the semifinished lens with asuitable adhesive material, and this block has three holes which arealigned with the cylinder axis, the center hole lying on the opticalcenter. The block is gripped in a collet and the blank swept by arotating grinding wheel. The diameter of the wheel together with theangle of the wheel with respect to the other side of the blankdetermines one radius of the toric surface; the other radius of thetoric surface is determined by the curve through which the wheel isswept over such other side of the blank. The blank is then ground andpolished with standard lapping equipment, using tools precut tocorrespond with the toric surface generated by the grinder, after whichthe lens is removed from the block and returned to the technician. Itshould be noted that all of the grinding and finishing operations havebeen performed on the entire semi-finished blank.

At this time the technician determines and marks the mechanical centerof the blank and also marks a horizontal axis line through themechanical center of the lens, and the blank is cut and chipped to itsultimate edge form, but left approximately one millimeter over-size. Theblank is then mounted into an alignment fixture, by visual alignmentbased on the marked mechanical center and horizontal axis, and placed inan edging machine which is cam controlled to produce the finished lensof the required size and contour.

It will be apparent from the foregoing, which is but a generaldescription of present methods, that the optical laboratory technicianmust spend considerable time and effort in measuring, marking andaligning the semi-finished blank, and that the rear surface iscompletely finished to prescription before the semi-finished blank iscut to its ultimate contour. Considerable time and expensive 3 labor ofa skilled technician is required, the grinding and finishing lappingoperations are performed over substantially the entire area of thesemi-finished blank, the tech nician spends further time preparing andmounting the blank in the alignment fixture, and then it is possible inthe edge cutting operation that the blank may be broken.

Accordingly, the primary purpose of this invention is to provide a novelmethod and novel apparatus according to which a technician can rapidlydetermine the ultimate mechanical center and the ultimate optical centerof the finished edged lens, and secure a plug on the lens properlyreferenced to each of these centers While taking into account therequired cylinder axis; then the semifinished blank, for the purposes ofreducing grinding and polishing time can be reduced in size to a smallersemifinished blank having its area balanced about the ultimatemechanical center of the lens; after which the prescribed surface, inits more frequent form a toric surface, is formed on the blank followedby finished grinding, polishing and edging to produce the finished lensready for fitting in the frame.

Another object of the invention is to provide a novel method ofprocessing multifocal ophthalmic lenses in which the ultimate mechanicalcenter of the finished lens is determined on the semi-finished lensblank by viewing the multifocal segments of the blank simultaneouslywith a target which appears coincident in position with the segments, amold fixture is oriented on the semifinished blank in predeterminedalignment with the ultimate optical center of the finished lens and afurther mold fixture is oriented on the semi-finished blank in apredetermined alignment with the ultimate mechanical center and offsetfrom the optical center of the blank as referenced from the target,including azimuth correction according to the cylinder prescription. Aplug is then moulded or cast between these fixtures which, uponhardening, is separated from such fixtures, and this plug is employed inaligning and holding the blank during generating, lapping andpreliminary edging operations.

Another object of the invention is to provide novel apparatus whichmounts a semi-finished lens blank, projects a target suitable forreferencing the multifocal segment of the blank, provides for alignmentof the blank with respect to the target, and also provides for preciselocation of moulding fixtures on the blank with respect to themechanical center, optical center and horizontal axis as determined byvisual comparison on the target and the blank, and including means forrelative rotation between these fixtures and the blank to include theprescribed cylinder axis in the positioning of the fixtures on the lens'blank whereby a moulded referencing plug may be formed, such thatgenerating of the prescribed optical surface on the blank can beaccomplished with reference to the ultimate optical center and edging ofthe blank to its finished form can be accomplished with reference to theultimate mechanical center.

A further object of the invention is to provide novel apparatus by meansof which a reference in the form of a plug is mounted on a finishedsurface of a finished lens blank, an outer surface of the plug providinga reference to the ultimate optical center of the finished lens and theinner surface of the plug providing a reference to the ultimatemechanical center of the finished lens, all in a continuous operationand under the control of a single unskilled operator, whereby a finishedlens can be produced by simple mechanical operations performed on thelens blank with reference plug being attached and used for alignmentpurposes in such subsequent mechanical operations.

Another object of the invention is to provide novel apparatus foratfixing to a semi-finished lens blank index or reference means whichare aligned with, respectively, the ultimate mechanical center of thefinished lens as it is located on the blank, the ultimate optical centerof 4 the finished lens as it is located on the blank, and with theintended horizontal axis.

A further object of this invention is to provide a novel method ofprocessing ophthalmic lenses according to prescription, wherein theprescription is translated into predetermined locations of holding andaligning surfaces, such surfaces are thereby properly located on asemifinished lens blank and then a plug bearing such surfaces isutilized by workmen unskilled in the ophthalmic art properly to hold andlocate the blank while the prescribed optical surface is generated,ground and polished and while a finished lens is formed from the blankwith its edge or contour properly referenced to the prescribed locationof the optical and mechanical center and the contour of the finishedlens.

Still another object is to employ a single cast plug for facilitatingthe formation of the prescribed optical surface on a lens blank and thecontrol of the final edge contour thereof, the latter being accomplishedby referral to the mechanical center reference and horizontal axisreference on the plug.

Other objects and advantages of the invention will be apparent from thefollowing description, the accompanying drawings and the appendedclaims.

In the drawings:

FIG. 1 is a view of a semi-finished blank of the improved multifocaltype for processing in accordance with the invention to form anophthalmic lens according to prescription;

FIG. 2 is a view of the semi-finished blank, showing the manner in whichan alignment target is viewed and the bi-focal segment of the blank islocated with respect to this target;

FIG. 3 is a sectional view of the semi-finished blank showing theconcave side of the blank supported by a round pin supported in atransparent lens window with an outer mold being associated with theconvex side of the blank, this mold providing the die face forreferencing the optical center on the molded plug;

FIG. 4 is a similar view showing the inner mold associated with theconvex side of the blank for referencing the mechanical center on themolded plug;

FIG. 5 is a cross-sectional view through the semifinished lens blank andmolded reference plug adhering to the convex side of the blank, showingthe tapered inner core, the conical side face of which is a referencefor the mechanical center, the exterior plug side face referencing theoptical center, the latter surface having key slots for receiving matingparts of a toric generator and a somewhat centrally located key slot forreferencing the horizontal axis and positioning the blank forpreliminary edge shaping and final edging operations;

FIG. 6 is a top plan view of this assembly of bland and reference plug;

FIGS. 7 and 8 are sectional views taken at right angles to each otherthrough the center of the finished lens and illustrating the generalarrangements of the toric surface formed on the rear of the dens as wellas a suitable finished edge;

FIG. 9 is a fragmentary and schematic view showing the general operationof the lens blank positioning station of a contemplated embodiment ofblocker for a semifinished blank of the multifocal type having referenceflats for orienting and positioning the blank in a predetermined manner;

FIG. 10 is a perspective view of another embodiment of blocker forlocating and molding the reference plug on the convex finished side of asemi-finished blank;

FIG. 11 is a front elevational view of this blocker;

FIG. 12. is an enlarged fragmentary view partly in section of theturntable assembly for the lens mounting assemblies;

FIG. 13 is a fragmentary plan view of the blocker with certain partsbroken away and removed taken along the lines 13-13 of FIG. 11;

FIG. 14 is a fragmentary sectional view taken through the lens mountingstation and showing the pressure inducing lever means for clamping alens blank taken along the lines 1313 of FIG. 11;

FIG. 15 is an enlarged fragmentary sectional view of the latch mechanismemployed for releasably locking the turntable of the blocker in eitherthe lens mounting position or plug molding position as viewed along theline 1515 of FIG. 13;

FIG. 16 is a bottom plan view of this latch plan mechanism view alongthe line 16-16 of FIG. 15;

FIG. 17 is a sectional view taken along the line 1717 of FIG. 16;

FIG. 18 is a fragmentary enlarged sectional view through the lensmounting station showing the relative disposition with respect to theviewing station, lamp assembly therefor and clamping lever for actuatingthe lens mounting assembly;

FIG. 19 is a top plan view partly broken away of the target and lensblank viewer along line 1919 of FIG. 18;

FIG. 20 is an enlarged fragmentary sectional view through part of theplug molding station showing the details of the dies employed in moldingthe referencing P FIG. 21 is a similar view of the dies associated withone another and with a lens blank ready for molding the referencingplug;

FIG. 22 is a sectional view taken along the line 2222 of FIG. 20;

FIG. 23 is a top plan view of the mechanism for shifting the inner diemember relative to the outer die member;

FIG. 24 is a fragmentary elevational view taken along line 2424 of FIG.23;

FIG. 25 is a fragmentary view taken along the line 25-25 of FIG. 23;

FIG. 26 is an enlarged fragmentary sectional view of a striker mechanismfor assuring the separation of the lens blank and plug assembly from themolds;

FIG. 27 is a fragmentary plan view of the turntable indexing wheelshowing the latching means for the turntable for determining thepositioning thereof at the lens blank plug assembly ejector station;

FIG. 28 is a schematic wiring diagram of the blocker;

FIG. 29 is a somewhat diagrammatic illustration of contouring apparatusused to form the edge contour on the blank as shown in FIG. 6;

FIG. 30 is an enlarged fragmentary view showing the holding means of theblank and plug assembly in apparatus of this type;

FIG. 31 is a schematic plan view of a typical toric surface generatorused in the method of this invention;

FIG. 32 is an enlarged fragmentary sectional view showing the chuckingmeans for this toric generator;

FIG. 33 is a schematic elevational View partly in section showingmechanism for removing radially exterior portions of the reference plugprior to the final edging of the blank;

FIG. 34 shows the association of this mechanism with the plug during theremoval operation;

FIG. 35 is a top plan view of the blank and plug assembly showingportions of the plug removed.

FIG. 36 is a perspective View showing the general manner in which theassembly of the blank and plug is engaged with conventional apparatusfor grinding and polishing the generated surface of the blank;

FIG. 37 is an enlarged elevational view of the chucking means of theblank and plug assembly of apparatus of this type;

FIG. 38 is a somewhat schematic view of the finished edge grindingapparatus;

FIG. 39 is another form of chucking means that may be employed, forexample, in the toric surfacer;

FIG. 40 is a top plan view thereof with certain parts removed;

FIG. 41 is another form of chucking means that may be utilized as, forexample, in the sphere surfacer; and

FIG. 42 is a top plan view thereof.

Referring to the drawings, which illustrate the steps of the method anda preferred embodiment of novel apparatus for performing certain stepsin the method, a typical semi-finished lens blank 10 is shown in FIGS. 1and 2 in the condition in which it is received from the supplier by theoptical laboratory. For purposes of illustration and explanation, theblank is shown as a bifocal blank having the main portion of one indexof refraction and a bifocal segment 12 of a diiferent index ofrefraction. In the blank illustrated, the front or outer surface, inother words, that surface which would be on the exterior of the finishedspectacles, is finished to a predetermined contour, usually spherical,and the rear surface 15 (FIG. 3) is that which has the prescribedoptical surface formed in accordance with the necessary opticalcorrections for the individual eyes of the ultimate wearer of thespectacles. It is possible that this arrangement can be reversed withthe multifocal segment on a rear finished surface, and the prescriptionsurface formed on the front, but this is unusual.

As explained, this prescription surface 15a (FIGS. 7 and 8) in mostcases is a toric surface, having one radius of curvature across the lensin one direction (FIG. 7) and a different radius of curvature in adirection of right angles (FIG. 8). These two directions are at rightangles to each other, and the amount by which the cylinder axis istilted (with respect to a horizontal line across the finished lens whenmounted) is expressed in terms of degrees.

Following mounting of the blank 10, the technician then positions a plugforming mold including cores or dies 24 and 26 on the front of convexsurface of the blank 10. This mold is defined by an external mold 24which serves to contour the plug with an optical axis reference and aninternal mold 26 which serves to contour the plug with the mechanicalcenter reference. These molds 24 and 26 will also have been alignedazimuthally with respect to a lens blank 10 and, more specifically, withthe horizontal reference axis according to the prescribed cylinder axis.

Thus, the optical center is first located withrespect to the segment 12and then the mechanical center is located with respect to the opticalcenter. The horizontal axis reference is maintained without changeregardless of all other changes in the core position during molding orblocking. This horizontal reference is, as explained, parallel to thetop of the segment line. The means for molding the reference for thecylinder axis is also adapted to be adjusted to the required axis beforethe core 26 is lowered into contact with the lens blank 10.

A reference plug 30 is then cast through the employment of suitablematerial, as for example, a low melting point alloy which is poured inmolten state between the molds 24 and 26 over the front surface of theblank 10. One suitable type of bonding alloy, which provides therequisite adherence to the lens surface, is an antimonylead compound (orthe like) having a melting point of around 158' F. This bonding materialhardens rapidly, for example, within about 30 seconds. On setting andhardening of the reference plug 30, the molds 24 and 26 aredisassociated from the assembly of lens blank 10 and reference plug 30.

The assembly upon completion will have the plug 30 located with respectto the lens blank 10 whereby the external surface 32 serves as theoptical center reference. The axial center line of the optical centerreference 32 contains the ultimate optical center of the finished lens.The reference plug 30 is formed with an inner somewhat conical surface34 serving as the mechanical center reference. The axial center line ofthe mechanical center reference 34 contains the ultimate mechanicalcenter of the finished lens. Cavity or key slot 36 is formed in the plug30 having its azimuthal position in fixed relation to the horizontalposition or axis reference of the mounted finished lens, i.e., with thetop of segment 12 horizontal. A pair of diametrically opposed key slots38 is formed in the exterior of the plug 30 and cooperate with thechecking means of a toric generator duly described shortly. The radialkey slot 40 cooperates with the chucking means of the smoothing andpolishing apparatus to be described shortly.

In FIG. 9, a semi-finished lens blank is somewhat automatically alignedand mounted in accordance with one embodiment of this invention throughthe employment of referencing or positioning flats 16 and 18 adapted tocooperate with mating parts of the aligning mechanism 22 of a blocker.This blocker may otherwise assume the form of the blocker 60 to bedescribed in detail herein. Thus, the mechanism 22 will include twopairs of adjustable and resilient clamping members. One of the clampingmembers cooperates with flat 16 and includes the gripping jaws 42 and44, the former being spring biased by means of the spring 46 to providethe desired degree of resiliency. The other jaw 44 is coupled with alongitudinally displaceable shaft 48 supported by a fixed support 52.The free outer end of the shaft 48 is conveniently coupled with a dial54 through a suitable splined connection (not shown) or other suitablecoupling whereby the dial remains associated with a fixed face. Thisface, 56, together with the dial 54, may conveniently include suitableindicia with index marks whereby the relative rotational displacement ofthese parts can be readily noted. The other cooperating clamping memberis composed of essentially identical parts and for this reason will notbe described but will be identified in the drawings through the use ofthe same numerals with accompanying primes. 'It should be evident thatcontrolling the position of the flats 44 and 44' through the dials willserve to locate the lens blank precisely in an intended position forcasting the molded plug previously described.

The lens blank 10 will have been supplied with the reference flats 16and 18 accurately positioned with respect to the vertical and horizontallocation of the segment 12. Such references replace the visual alignmentof the segment with the target in the blocker. These edge references mayalso serve to locate the segment in the X and Y axis directions, thusavoiding the need to align the segment visually with a viewing device.Each of the two fiat edge reference surfaces shown in FIG. 9 could be acontrolled constant distance from the reading segment outline. Theseedge references then take the place of the actual segment as far ascontrolling the position and orientation of the blank with respect tothe optical center mold 110. Such references would avoid the need toalign the segment visually with the target in the blocker.

Reference is now made to the blocker 60 which is adapted to receive thesemi-finished lens blank 10 and align it for placement of a moldedreference plug 30 thereon. The blocker 60 includes a lens blank mountingstation 62 at which the lens blank 10 is aligned and its convex surfacecorrectly positioned against mold 24 for properly performing subsequentoperations while in the blocker. Towards this end, a target viewingstation 64 is associated therewith for providing a referencing targetand index 20. The blocker 60 is designed and constructed on a turntableprinciple whereby the mounted lens blank 10 and mold 24 may be turned toa plug molding station 66. Here the mold 26 is properly oriented andpositioned on the convex side of the lens blank 10. The reference plug30 is thereafter poured and set in an automatic fashion once the pouringhas been initiated. A low melting point alloy dispensing station 68supplies the material from which the plug 30 is formed.

The blocker 60 deploys its stations on a selected support through thebase 70 in the form of an inverted tray having a top panel 72 anddownwardly depending side aprons 74, 76, 78 and 80. A turntable assembly81 is mounted centrally of the top panel 72. This assembly includes atable 82 of substantially oblong configuration having at each of itsends a pair of identical lens mounting assemblies 84 and 86. The table82 at its relative center is suitably keyed to a rotatable shaft 88.This shaft is supported in an upright position, and its pivotal movementis aiforded by a pair of ball bearings and 92. These bearings areinterposed between the shaft 88 and an upright standard 94 anchored tothe top panel 72. The lower end of the shaft 88 has keyed thereto anindex wheel 96. The upper face of the index wheel is provided with apair of diametrically opposed indexing holes 98 adapted to receive aspring biased indexing lug 100 longitudinally shiftable in aperture 102under the bias of spring 104 in the top panel 72. The engagement of thelower end of the plug 100 with either of the mating holes 98 determinesthe placement of either of the lens mounting assemblies 84 or 86 at thelens blank ejector station the operation of which will be described.

Referring now to the lens mounting assembly 84 and 8 6 which will bearcorresponding numerals for identical parts, it will be noted that eachis provided with a dial bearing a scale of angles from zero to 180 onone half of the dial face and then again zero to 180 on the second halffor purposes of introducing the prescribed cylinder axis. This dial isrotatably mounted on the turntable 82 and suitable retained associatedtherewith, as shown. The dial is provided with a central opening 112 topermit viewing therethrough in order to properly position a lens blank10 in the lens mounting assemblies 84 or 86. Each of the lens mountingassemblies 84 or 86 includes a downwardly depending shaft 114 suitablyanchored to the turntable 82. This shaft serves to mount a collar 11 6which is afforded limited longitudinal movement with respect to theshaft by means of the pin 118 extending from the shaft into alongitudinally extending slot 120 provided in the walls of the collar.In a manner to be described in detail shortly lens blanks 10 ofdifferent thicknesses are adapted to be received by either of the lensmounting assemblies 84 and 86 through the operation of latch assembliesincluding the series of circumferentially extending radial flanges 122each having a forward camming face 124 to facilitate the latchingfunction. A spring biased latch 126 engages with these flanges; and, inthis connection, is provided with a latch face 128 and, at the sametime, a bevelled face 130 for riding against the bevel faces 124. Thelatch 126 is biased towards the shaft 116 by means of the spring 132. Ahandle 134 pivotal about pin 136 is adapted to shift the latch radiallyoutwardly against the bias of the spring 132 by camming against theradial flange 138 of the latch 126.

A standard 140 extends laterally from the collar 116 and is adapted tobe resiliently supported thereby. In this connection, the standard isprovided with a bore 142 enlarged into bore sections 144 and 146 whichdefine stepped shoulders 148 and 150 A pair of concentric springs 152and 154 are disposed'exteriorly of the collar 116 and within the'boresections. The spring 152 is biased at one end against a stepped washer156 which, in turn, is limited in its upward movement with respect tothe standard 140 by means of a retaining ring 158. The lower end of thisspring is biased against a Washer 160 which, in turn, is limited in itsdownward movement with respect to the collar 116 by means of thelockwasher 162. The outer concentric spring 154 is biased at one endagainst the washer v156 and, at the other end, against a washer 164, inturn, limited in its downward movement with respect to the standard 140.Thus, the arrangement of parts depicted by FIG. 18 will permit upwardmovement of the collar 116 relative to the standard 140 for purposes 9of permitting the latch 126 to engage with the flanges 122.

A spring biased pin 168 extends into the bore 142 of the standard intoan accommodating recess 170 in the exterior of the collar 116 forpurposes of cooperating in preventing undesirable rotational movement ofthe collar 116 relative to the standard 140'.

The standard 140 is also provided with an enlarged bore opening 174terminating at its upper end in a radially extending flange 176. Thisbore opening 174 conveniently receives a tubular member 178 formedexteriorly with a shoulder 180. The top of the tubular member 178 servesto receive a glass transparent window 182 in a suitable permanentfashion. This window has projecting upwardly and outwardly therefrom apin 184. This pin 184 serves to receive the concave face of the lensblank 10. The tubular member 178 is spring biased in a downwardlydirection by means of a spring 186 biased between shoulder 180 andflange 176. The tubular member 178 is adapted to be shifted upwardlyagainst the bias of the spring 186 for purposes of accommodating lensblanks of different thicknesses. With this in mind, the tubular memberis provided with a cut-out portion 188 extending obliquely with respectto the horizontal for purposes of receiving an inwardly extending pin190 projecting from the standard 140. This pin 190 is adapted to bereceived by one of a series of accommodating slotted portions 192 of therecess portion 188.

The lens blank 10 is, accordingly, adapted to be mounted in place in theselected lens mounting assembly 84 or 86 by initially placing the lensblank 10 on the pm 184 or, alternatively, against the lowercircumferentially extending edge of the dial 110. The collar 116 is thenshifted upwardly on the shaft 114 until the latch 126 engages theappropriate flange 122. If desired or necessary, the amount of pressureexerted by the pin 124 and cooperating lower edge of the dial 110against the blank 10 may be regulated by selecting the appropriateflangs 122 for latching with the latch 126 or, for that matter, theappropriate slotted portion 192 for receiving the inwardly extending pin190.

A lever assembly 196 is adapted to be actuated for purposes of causingthis relative vertical shifting of the collar 116 and consequentsecurement of a lens blank 10 within the particular lens mountingassembly 84 or 86. The assembly 196 includes a lever 198 pivotal on anupstanding bracket 200 by means of a pivot pin 202. he lower end 204 ofthe lever 198 straddles a pin 206 which supports a platform 208 adaptedto engage the base of the collar 116. This pin is biased in a downwardlydirection by means of a spring 210 biased against the platform 72 and aradially extending retaining ring 212. Thus, by depressing the lever 198with manual pressure, the lower end thereof will raise the platform 204and, consequently, elevate the collar 116 in securing a lens blank 10between the pin 184 and lower edge of the dial 110.

The lens blank 10 is properly positioned in the selected lens mountingassembly 84 or 86 through the employment of the target viewing station64. This assembly includes an optical system housed chiefly withinhouslng 216. This optical system includes a lamp 218 which, whenenergized, is adapted to have its rays reflected by a pair of reflectingsurfaces or mirrors 220 and 222. These rays are adapted to pass througha pair of cooperating reticles 224 and 226 and ultimately to the eye ofthe viewer. The reticle 224 functions as the target reticle whereas thereticle 226 functions as the scale reticle. Both reticles are formed ofphotographic negatives with a black background and white lines andnumerals adapted to transmit the light rays. In this connection, themaster of both scales can be initially produced on an enlarged scale andthen reduced to size to form the finished product. The image transmittedthrough the reticle 224 is then reflected by means of the reflectingsurface of mirror 228 and transmitted through the magnifying lens 230and then reflected by the reflecting surface mirror 232 from whence itpasses through the lens 234 to the eye of the viewer. The imagetransmitted through the reticle 226 also passes through the lens 230 insuperimposed relation to the image emanating from the reticle 224 and isthen reflected by the mirror 232 and also passes through the lens 234 tothe eye of the viewer.

All of the parts constituting the described optical system may besuitably mounted in the housing 216 by one of many known techniquestypified by that illustrated in FIG. 18. With respect to the targetreticle 224, however, an adjustable mounting is provided whereby thereticle 224 may be adjusted in transverse directions while in ahorizontal plane. Thus, this reticle 224 may be supported by means of aplate 238 provided on its top surface with teeth 240 for purposes ofacting as a rack. These teeth 240 are, in turn, adapted to mesh with theteeth of a geared portion 242 and 244 acting as a pinion. A knob 246extends outwardly of this geared pinion whereby turning of the knobcauses corresponding movement of the pinion and, consequently, the rackportion of the plate which supports the reticle 224.

The inner end of the pinion 241 extends through an accommodating bore ofa bracket 243. A retaining ring 245, washers 247 and 249, together withcompression spring 251 serves to assure the proper meshing of the piniongeared portion 242 and 244 with the rack portion 240 of the plate 238.In this manner, it is possible to accurately locate the optical centeraccording to prescription by shifting the target reticle 224 relative tothe scale reticle 226.

Transverse movement of the reticle 224 is accomplished by means of asecond knob controlted actuator including an internally threaded tube250 connected with the plate 238. This tube is permitted longitudinalmovement relative to a boss 252 extending inwardly of the housing 216but is not permitted relative rotational movement with respect theretoby means of the screw 254 extending into a longitudinally extending slot256 in the tube. An externally threaded screw 258 is received by thetube 250 and, when turned, is adapted to shift the plate 238 and,consequently, the reticle 224. The outwardly projecting end of thethreaded screw 258 conveniently mounts a handle 260 which facilitatesthe turning of the screw.

The segment 12 of the lens blank 10 is then aligned with the targetreticle. To this end, a lamp assembly 270 directs a suitably intenselight beam through the window 182 of the lens mounting assembly to castan image of the segment 12 onto the reflecting surface or mirror 272from whence it is reflected onto the mirror 232 and then reflected insuch a manner that it passes along the optical center through the lens234 to the eye of the viewer.

When the cylinder axis has been set to prescription by means of the dialand the movable target reticle 224 has been displaced relative to thesubstantially stationary reticle 226 to locate the disposition of thesegment 12 relative to the optical center and the lens blank 10accurately located and clamped in the lens mounting assembly 84 and 86,the turntable 81 is shifted to place the mounted lens blank 10 at theplug molding station 66. An indexing unit 276 cooperates with theindexing wheel 96 keyed to the base of the shaft 88 of the turntableassembly 81. This indexing unit includes a slide lock 27'8 adapted to beplaced in the accommodating recesses 280 of the indexing wheel 96 uponattainment of either the lens mounting position or plug molding positionby the turntable assembly 81. This slide lock 278 is slideably mountedby a carrier 282 of the locking unit 276 and is adapted to be actuatedby crank arm 284 pivotally connected with the slide and keyed to a shaft286 also having secured thereto a lever 288 disposed on the other orupper side of the base panel 72. The slide lock 278 is adapted to besecured in the locked position through the operation of a locking pin290 adapted to be disposed in an accommodating recess 292 in the slide278. This pin extends from a piston

